The evolution of tRNA-Leu genes in animal mitochondrial genomes
The evolution of tRNA-Leu genes in animal mitochondrial genomes
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DOI：
10.1007/s00239-003-2494-6
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发表时间：
2003-10-01
影响因子：
3.9
通讯作者：
Rattray, M
中科院分区：
文献类型：
--
作者：
Higgs, PG;Jameson, D;Rattray, M
动物线粒体基因组通常有两个亮氨酸转移rna：一个具有反密码子UAG，翻译四密码子家族的CUN。另一个带反密码子UAA，翻译双密码子家族的UUR。这两个基因在第三个反密码子位置上一定不同，但在一些物种中，这些基因在许多其他位点上不同，这表明这些基因已经独立了很长时间。线粒体基因组中基因的重复和缺失在后生动物的进化过程中经常发生。如果tRNA- leu基因被复制并在反密码子中发生替换，这将有效地将一种tRNA转变为另一种tRNA。第二种tRNA类型的原始拷贝可能会因为基因组中其他地方的缺失而丢失。有几组物种的两个tRNA-Leu基因在基因组上彼此相邻（或非常接近），这表明发生了串联复制。在这里，我们使用rna特异性系统发育方法来确定这两个基因的进化树。我们提供的证据表明，tRNA-Leu基因的复制、反密码子突变和缺失过程在后生动物的进化过程中至少发生了5次——一次在所有原口动物的共同祖先中，一次在棘皮动物和半足动物的共同祖先中，一次在寄居蟹中，两次在软体动物中独立发生。
Animal mitochondrial genomes usually have two transfer RNAs for leucine: one, with anticodon UAG, translates the four-codon family CUN. while the other, with anticodon UAA, translates the two-codon family UUR. These two genes must differ at the third anticodon position, but in some species the genes differ at many additional sites, indicating that these genes have been independent for a long time. Duplication and deletion of genes in mitochondrial genomes occur frequently during the evolution of the Metazoa. If a tRNA-Leu gene were duplicated and a substitution occurred in the anticodon, this would effectively turn one type of tRNA into the other. The original copy of the second tRNA type might then be lost by a deletion elsewhere in the genome. There are several groups of species in which the two tRNA-Leu genes occur next to one another (or very close) on the genome, which suggests that tandem duplication has occurred. Here we use RNA-specific phylogenetic methods to determine evolutionary trees for both genes. We present evidence that the process of duplication, anticodon mutation, and deletion of tRNA-Leu genes has occurred at least five times during the evolution of the metazoa-once in the common ancestor of all protostomes, once in the common ancestor of echinoderms and hemichordates, once in the hermit crab, and twice independently in mollusks.